This invention relates to a solar energy collecting means, and more particularly to a collector which utilizes the principles of heat conduction to a heat transfer point external of the collection-absorption part of the collector.
The present art defines several well-known collectors, including simple, flat plate collectors for heat transfer to air, liquid, or both, as well as structured shapes for various transfer mediums.
Generally, the collectors described in known art are arranged to accept gaseous or liquid heat transfer medium from a supply system or manifold, and after heat collection and transfer to the medium, to discharge the heated medium to a return system or return manifold. Heat transfer occurs by convection and/or conduction, and is usually accomplished within the confines of the collector-absorption section of the device.
Heat transfer within the collector section is disadvantageous with a liquid system due to the high cost of providing a plurality of pipes similar to those shown in U.S. Pat. Nos. 2,133,649, 3,390,672, and 3,951,129.
Another disadvantage of known art using liquid mediums is the requirement for anti-freeze solutions and/or special expansion fittings to compensate for thermal stress at conduit connections. Despite these precautions, corrosion of internal conduit walls and the possibility of leakage within the collection section prevail.
Many flat plate collectors have specially coated surfaces which absorb solar rays efficiently. Concentrating collectors generally have a contoured surface to direct solar rays to a focal point or line which is within an absorption conduit or pipe similar to U.S. Pat. No. 3,968,786.
U.S. Pat. No. 3,951,129 shows a generally flat surface collector, said surface being modified with a "V" groove and specially treated with a coating for high efficiency solar ray absorption. This reference also teaches the use of monolithic construction with parallel conduits requiring a plurality of inlet and outlet connections for each conduit.
Specified for a different end use, and without collecting, concentrating or conducting means, U.S. Pat. No. 2,783,682 shows a plurality of different configurations used to structure, groove, or contour the surface.
Collectors or absorbers that are substantially planar (with or without structured surfaces) fall within the generic definition of "flat plate" construction, and it is noted that these collectors can only transmit heat at temperatures equal to, or les than, the temperature of the flat absorber surface.
The present invention teaches a unique method for transmitting heat at temperatures greater than the temperature of the reflector surface while retaining the simplicity of "flat plate" construction.